A fluidized bed gasification system which comprises a fluidized bed gasification reactor having a bottom ash discharge outlet below the reactor, wherein an L-valve is used to control the rate of bottom ash discharge. The L-valve uses an aeration port located on distal side of the L-valve vertical pipe at a location that is above the center line of the horizontal pipe. Also provided are methods of controlling the bottom ash discharge as well the fluidized reaction bed height of the system.

A gasifier may include a chamber wall defining a gasification chamber configured to allow gasification of feedstock material. The gasifier may also include an ash grate disposed in the gasification chamber. The gasifier may further include a rotary crusher disposed in the gasification chamber above the ash grate. The rotary crusher may include at least one crushing element. The rotary crusher may be configured to break apart, between the at least one crushing element and an opposing surface, the feedstock material responsive to rotation of the rotary crusher.

The present disclosure relates generally to a method for obtaining synthesis gas from a gasifier that has a low methane content. The synthesis gas is obtained as an extraction gas from the quench section of the gasifier, and can be utilized as feedstock for a variety of chemical production processes without the need for expensive pre-treatment to remove methane.

This invention involves with a gasification system, which includes a gasifier, which gasifier comprises a gasification chamber for producing syngas from coal slurry and a quench chamber for cooling the syngas from the gasification chamber. The mentioned gasification system also comprises preheater located in the quench chamber for utilizing heat in the quench chamber to preheat the coal slurry before the coal slurry enters the gasification chamber. Wherein, the preheater comprises a pipe device defining a passage for the coal slurry to pass through, the passage in communication with the gasification chamber and upstream of the gasification chamber in a flow direction of the coal slurry. This invention also involves with a preheater used in the mentioned gasification system and the gasification method of the mentioned gasification device.